Navy torpedoes are most commonly driven by a hot gas turbine. The driven gases are provided by a high heat, high pressure combustion chamber or boiler. The boiler commonly reaches a temperature of 1700 degrees fahrenheit and the pressure reaches 300 psi.
In order to supply fuel for running the boiler an injector extends into the boiler and is mounted to the boiler with some sort of sealing apparatus. The fuel that is commonly used is lithium sulfurhexafluoride which is desirable because of its high energy to volume ratio, but is undesirable because of its extreme corrosive effect on metals.
To deal with the hostile environment of the torpedo boiler the Navy has been using an injector assembly which utilizes a tungsten sealed injector within a hastelloy housing. The injector assembly is mounted by welding the hastelloy housing to an exterior stainless steel wall of the boiler. Even though the tungsten and hastelloy metals are the best known for withstanding the hostile environment the tungsten sometimes cracks and disassociates itself from the hastelloy housing due to the high heat and the corrosive effect of the high energy fuel utilized. This causes the seal to break, whereupon high pressure gases escape from the boiler.
In order to overcome the tungsten corrosion problem the Navy has been very desirous of using a ceramic injector. Ceramic injectors are well known in the prior art, and the right kind of ceramic injector will withstand the hostile high heat, high pressure, corrosive environment of a torpedo boiler. However, the prior art is silent on how to attach a ceramic injector to the boiler so that it can withstand the hostile environment. With prior art attachment devices the high heat expands the parts at different rates causing the parts to break away from one another, thus allowing high pressure gas to escape. For instance, where the ceramic injector is attached to a stainless steel boiler the boiler material expands away from the ceramic injector by a factor of 30 to 1. This leaves no chance to maintain a seal between the injector and the boiler by a direct welded connection. Prior art metal mounting apparatuses for ceramic injectors suffer the same problems, namely, a radical difference in expansion rates causing any sealing attempts to fail. What is needed is an apparatus for retaining the ceramic injector to the boiler so that it won't fail when subjected to the hostile environment which is necessary to make the torpedo efficient.